Purchased the black in size large - fit perfectly - the tape measure clocks me in at 24 inches, if that helps. The UK heatwave tried its best to defeat me all summer but this hat has kept me covered from festivals to gardening to run sessions.
Really well made, breathes really well and is lightweight to the point you forget it is on your head. Get it before it is gone. Another amazing ACG product this season! They really have been on strong form.